Shank protector for earth digging tool



June 1954 G. A. PETERSEN SHANK PROTECTOR FOR EARTH DIGGING 001.

2 Sheets-She 1 Filed Aug. 28, 1961 INVENTOR. GER/4L0 A. PETERSEN ATTOPNEY June 16, 1964 G. A. PETERSEN SHANK PROTECTOR FOR EARTH DIGGINGTOOL 2 Sheets-Sheet 2 Filed Aug. 28, 1961 IN VEN TOR.

. GERALD A. PETERSEN A 7'TORNEK United States Patent ()fi ice 13,137,352 Patented June 16., 1964 Calif.

Filed Aug. 28, 1961, Ser. No. 134,520 6 Claims. (Cl. 172713) Thisinvention relates to a new and improved protector for the shank plate ofan earth digging tool, such as an earth auger for rotary digging of ahole or a trenching or other digging machine.

At the present, various earth digging machines have incorporated thereinadjacent the end which performs the digging operation, a headorpermanent structure to which is fastened by means of bolts or othermeans a shank plate which is intended to be relatively permanent. Thefunction of the shank plate is to act in cooperation with one or moreearth digging teeth to hold the teeth on the machine in proper positionfor digging. The replaceable teeth absorb the major part of the wearoccasioned by the dig g action, such wear being compensated by reversingthe teeth when one surface thereof is worn and eventually by replacingthe teeth with new teeth. However, in practice it has been found thatexposed surfaces of the shank plate tend to come in contact with theearth being handled, particularly with rock, gravel and sand whichabrade certain surfaces of the shank plate. Eventually the shank platemay be worn out and must be replaced.

Accordingly, it is a principal object of the present invention toprovide a protector for exposed surfaces of a shank plate for a diggingtool, which protector absorbs the abrasive action heretofore mentionedand hence protects the shank against wear, thereby materially prolongingits life particularly in installations where the shank is subject toconsiderable abrasion.

The protector, which is the subject of the invention, is inexpensive andis a very readily replaceable shield fitting over the surfaces of theshank plate most subject to wear. Preferably,' such protector is formedof sheet metal or the like so that it may be replaced as frequently asrequired during the life of the tool without the necessity of replacingthe shank plate itself. Hence, a feature of the invention is the factthat use of the inexpensive pro tector preserves the life of therelatively expensiveshank plate.

Another feature of the invention is the fact that it may be rapidly andreadily installed on existing shank plates and does not require anycomplicated or expensive machining operation for installation, nor anyalteration of the shank plate or teethwhich affects their function.

Still another feature of the invention is the fact that, being of lightgauge metal, it may be pressed, bent, cut with shears, or otherwisedeformed to fit 'a' variety of shapes of shank plates and. toaccommodate variations in shank plates occasioned by wear, repairoperations or'malformations. i i

A still further feature of the invention is the fact that it is soconstructed that it cooperates with the tooth and the shank for properretention in place and does'not'require complicated or expensiveretaining'means.

A still further feature'of the invention is the factthat its use doesnot interfere in any way with the operation or efficiency of the earthdigging machine, nordoes it detract from the security of the fasteningof the tooth to the shank,nor make difficult the intentional removal ofthe tooth from the shank when the tooth needs replacement. a I

Other objects of the present invention will become apparent upon readingthe following specification and referring to the accompanying drawingsin which similar characters of reference represent corresponding partsin each of the several views.

In'the drawings:

FIG. 1 is an exploded perspective view of one form of the invention.

FIG. 2 .is a top plan thereof.

FIG. 3 is a side elevation thereof.

FIG. 4 is a front end elevational view thereof.

tion.

FIG. 6 is a top plan view thereof.

FIG. 7 is a side end elevational view thereof.

FIG. 8 is a bottom plan view thereof.

In the form of the invention shown in FIGS. 1 to 4, inclusive, the tooth11 consists of a tapered distal portion 12 having reversible cuttingedges 13 in a sense that converging top and bottom distal surfaces 14,16 are truncated at the front edge. 'Rearwardly at the top and bottomsurfaces 14, 16 are proximal prongs 17 or roots on either side of thetooth separated from each other by a rectangular slot 18 which extendsforwardly from the proximal end of the tooth. Each prong 17 has top andbottom surfaces 19, 21 which are preferably flat and which arepreferably parallel to each other butwhich may be slanted if desired.Vertical side walls 22 are formed defining the sides of slot 18 and aresilient insert 23, hereinafter described, presses against such walls22 to hold tooth 11 in its shank plate26. 1

Tooth 11 is received in shank plate 26 which is fastened by anyconvenient means to a permanent portion (not shown) ofthe earth diggingtool. The shape of shank plate 26 is subject to wide modification,depending upon the use of the tool in which it is installed. Thus, asillustrated herein, shank 26 receives a single tooth 11. However, itwillbe understood that in other installations asingle shank plate mayreceive a plurality of teeth, each tooth being preferably positioned ata proper angle with respect to the other teeth and with respect to thedirection of movement of the tool to perform the digging operation inthe most effective manner.

In the shank plate'26, illustrated in FIG. 1, there is a i the sidewalls of the slot. The top or upper member 29 is formed with a top wall32 on either side of web 28 and the lower member 31 is formed with thebottom wall 33 on either side of web 28. The spacing'between walls 32,33 is sufficient to accommodate the thickness of-the prongs 17 of tooth11.. Extending transversely horizontally through web 28 is a hole (notshown) which receives resilient insert 23 formed of rubber; neoprene, orthe like, which is preferably circular in cross-section. The length ofinsert 23 is substantially greater than the Width of web 28. Thus, ininstalling the tooth the prongs '17fare inserted in the opening oneither sideof web 28xand the. proximal ends of prongs 17 bend insert 23back and jam the insert between web 28 and the side walls 22, therebygripping the toothso that it cannot be readily dislodged.

In normal usage of earth digging equipment, dislodgment" of tooth 11will not occur. By reason of the resilient nature of insert 23,wear,;vibra tion' and the abrasive action of sand, gravel or rocks, inwhich the tool is digging, and the like, will not ordinarilycauseseparation of the tooth from the shank plate. '7 1 When it isnecessary to remove tooth 11 as, for'example,

when it is desired to reverse the tooth so that one cutting edge 13, maybe substituted for the other, or when it is necessary'for any reason toreplace tooth-11, the tooth is dislodged'from the shank plate by drivingit forwardly FIG. 5 is an exploded perspective view of a modifica- U byinserting a tool suitable for such purpose behind the proximal end ofprongs 17.

The foregoing described construction of tooth 11 and shank plate 26results in the major portion of the wear of the tool being absorbed bythe replaceable tooth 11. However, it is apparent that some of the wearwill be absorbed by the shank plate 26 and particularly the uppersurface 29 thereof, in that rocks, gravel, and the like, which are cutout of the earth by the tooth, pass over the top of the tooth and hencewear against the leading upper edge of the shank plate. With the passageof time this may necessitate replacement of the shank plate 26. Thepresent invention employs a protector 36 fitting over the wear surface29 of the shank plate 26, which protector absorbs the wear and hencemakes it unnecessary to replace the shank plate.

In the modification shown in FIGS. 1 to 4, inclusive, protector 36comprises a top portion 37, a bottom portion 33, and an interconnectingcentral portion 39. The protector 36 is preferably formed of sheet metaland can be deformed by bending, peening, cutting, etc. portion 39 has aWidth-substantially equal, but in no case greater than, the width ofslot 18. Top portion 37 has a width approximately equal, but in no casegreater than the width of upper portion 29 of shank plate 26, and has alength extending back from the leading edge of the shank plate asufficient distance so that all major Wear is absorbed. T he rearwardend of the top portion 37 is formed with a short tab 41 of reduced widthwhich cooperates with a rectangular transverse dimple -2 formed in thetop surface 29 of shank plate 26 to receive tab 41. The tab 41 is curveddownwardly to fit into and lock within dimple 42 to restrain dislodgmentof protector $6. The bottom portion 38 likewise has a width about equalto the width of the bottom portion 33 of shank plate 26 and a lengthsufficient to absorb the major portion of the wear on the bottom surfaceof'the shank plate. The tab 43 at the end of the bottom portion 38 issimilar to tab 41 and locks into a dimple 44 on the bottom 33 of theshank plate similar to that on the top thereof.

Thus, in use, the protector 36 is applied to shank plate 26 before tooth11 is installed. Once the tooth 11 is driven into position the protector36 is locked between Central tending semi-circular extension 61. The topand bottom surfaces 62, 64 of the shank plate converge rearwardly.

are dislodged by tooth 51 and passed up over shank plate 52.

Protector 66, which is the subject of this invention, is approximatelyarcuate in end elevation. protector 66 has a length sufiicient to coverthe major portion of surface 62 of the shank plate 52 which receives themajor wear and converges rearwardly in a triangular shape as viewed intop plan '(see FIG. 6). Surface 67 of protector 66 may be peened orotherwise deformed to form a depressed tab 69 locked into extension 61of aperture 6G to hold protector 66 in place. The forward edge 71 ofprotector 66 has a rectangular hole 72 conforming I to socket 69 andgenerally similar to front end 63. On

either side of protector 66 tabs 72 extend rearwardlyfrom the bottomedge of forward'edge 71 and grip against the bottom surface 64 to holdthe protector in place. Projections 58 likewise prevent totaldislodgement of the protector. By reason of the deformable nature of thesheet metal of which protector 66 is made and the fact that it may becut with tin ships as required, protector66 is adaptable to a widevariety of shapes of shank plates 52 and a variety of differentconfigurations wherein the permanent portion of the tool is attached tothe shank plate 52. A i

In use, protector 66 is slipped over shank plate 52 and deformed in suchmanner as toembrace the shank plate as has been explained. The rearwardend of the top of the protector is peened to form tab 69 fitting intocut-out 61 to hold the protector in place. Where projections 58 are usedon tooth 51 they prevent total dislodgement of the protector in aforward direction. As in the case of the preceding modification, theprotector 66 absorhsmost of the wear which would otherwise be receivedby the the end of slot 18 and the forward end of web 28, so that itcannot be removed as long as the tooth is in place. To further securethe protector in position, the tabs 41, 43 on the end of top and bottomportions 37, 38 are peened into the dimples 42, 44. Because the sheetmetal of which the protector 3.6 is constructed is deformable, theprotector will accommodate considerable variation in the shape of theshank plate 26. Further, it may be cut with a tin snip or the like ifnecessary. 7

Since protector 36 is expendable it may be replaced whenever required,the shank plate 26 being protected so that it need not'be replaced.

In the form of the invention shown in FIGS. 5 to 8, inclusive, adifferent form of tooth 51 is used and the shank plate 52correspondingly is differently constructed. Thus,

tooth 51 shown in this modification consists of converging distal topand bottom faces 53, 54, truncated at the front edge 56.- Rearwardly ofthe top and bottom surfaces 53, 54 is a proximal root 57 which ispreferably rectangular in cross-section. In certain forms of teeth ofthis general type there is on either side of the tooth, a substanti allyrectangular lateral projection 58. Root 57 is received 7 in socket 59 inthe shank plate 52. It will be understood that the use of projections 58is optional.

The shank plate 52 is here illustrated as receiving a v single tooth 51,it being understood that a plurality of teeth may be received. The shankplate 52 is formed with a rectangular socket 59 of a cross-section toreceive root 57 with a driving fit and a lengthsufficient to accommodatethe length of root 57 with a slight clearance. Rearwardly v of socket 59the shank plate is cut away in an aperture 69 which preferably has aforwardly exto retain said protector in place so long as said toothisshank plate 52 and can be replaced as frequently as re quired, therebypreserving the shank plate. 7

Although the foregoing. invention has been described in some detail, byway of illustration and example for pur- 1 poses of clarity ofunderstanding, it is understood that certain changes and modificationsmay be practiced within the spirit of the invention and scope of the.appended claims.

What is claimed is: V i i 1. In combination in an. earth-digging tool,"a shank plate formed'with a socket, a tooth formed of a hard, unitarypiece of material and having its proximal end shaped to fit into and tobe retained within said socket,

and a replaceable protector for said shank plate, said pro;

tector comprising a deformable top portion fittingover the top of saidshank plate, said shank plate beingformed I with a dimple in proximityto the rearward edge of said top portion, said protector being indentedto fit within and be retained in cooperation with said dimple, said I, Iprotector having at least one bottom portion and at least oneinterconnecting portion interconnecting said top por-A 'tion and saidbottom portion, said bottom. portion fitting under a part of the bottomof said shank plate, said top" and bottom portions squeezing against thetop andbote tom of said shank plate to retain said protector on said 7shank plate, said interconnecting portion being positioned adjacent thearea in which said proximal end enters said socket, said toothand shankplate being formed with parts thereofon opposite sides of saidinterconnecting portion positioned in said socket.

2. The combination of claim 1, in which said proximal:

At its top 67 end of said tooth is bifurcated and said interconnectingportion fits between the bifurcations of said proximal end. 7 a a 3. Incombination in an earth digging tool, a shank plate formed with at leastone socket, a tooth formed of a hard, unitary piece of materialandhaving'a slot in its proximal portion dividing said proximal portioninto a pair of roots, at least one of said roots fitting within saidsocket, retaining means retaining said root in said socket, and aprotector formed of thin deformable material having a top portionfitting over a portion of the top of said shank plate, aninterconnecting portion fitting between said roots and a bottom portionfitting under a portion of the bottom of said shank.

4. The combination'of claim 3, in which said top of said shank plate isformed with a depression and said top portion of said protector isdeformed to fit within said depression.

5. In combination in an earth digging tool, a shank plate formed with apair of sockets and having a web tom of said shank. v

6. In an earth digging tool, a shank formed with a socket, a toothformed with a root fitting into i said socket and a replaceableprotector of deformable material having a top portion fitting over andprotectingfrom wear at least a portion of the top of said shank plate,said protector having bottom tabs fitting-under said shank plate, thetop surface of said shank plate being formed with an aperture and saidtop portion of said protector being deformed to fitwithin said aperture,the portion of said protector interconnecting said top portion andbottom tabs formed with a hole of the samecross-section as said socketand overlying said socket, said tooth formed with an enlarged portionadjacent to said socket to engage said portion of said protector toretain said protectorin place against total dislodgment so long as saidtooth is in said position in said shank plate.

References Cited in the file of thispatent UNITED STATES PATENTS2,702,712

Snyder Feb. 22, 19 55, Launder Jan. 10, 1956 Petersen s Jan. 2ft, 196 1'

1. IN COMBINATION IN AN EARTH-DIGGING TOOL, A SHANK PLATE FORMED WITH ASOCKET, A TOOTH FORMED OF A HARD, UNITARY PIECE OF MATERIAL AND HAVINGITS PROXIMAL END SHAPED TO FIT INTO AND TO BE RETAINED WITHIN SAIDSOCKET, AND A REPLACEABLE PROTECTOR FOR SAID SHANK PLATE, SAID PROTECTORCOMPRISING A DEFORMABLE TOP PORTION FITTING OVER THE TOP OF SAID SHANKPLATE, SAID SHANK PLATE BEING FORMED WITH A DIMPLE IN PROXIMITY TO THEREARWARD EDGE OF SAID TOP PORTION, SAID PROTECTOR BEING INDENTED TO FITWITHIN AND BE RETAINED IN COOPERATION WITH SAID DIMPLE, SAID PROTECTORHAVING AT LEAST ONE BOTTOM PORTION AND AT LEAST ONE INTERCONNECTINGPORTION INTERCONNECTING SAID TOP PORTION AND SAID BOTTOM PORTION, SAIDBOTTOM PORTION FITTING UNDER A PART OF THE BOTTOM OF SAID SHANK PLATE,SAID TOP AND BOTTOM PORTIONS SQUEEZING AGAINST THE TOP AND BOTTOM OFSAID SHANK PLATE TO RETAIN SAID PROTECTOR ON SAID SHANK PLATE, SAIDINTERCONNECTING PORTION BEING POSITIONED ADJACENT THE AREA IN WHICH SAIDPROXIMAL END ENTERS SAID SOCKET, SAID TOOTH AND SHANK PLATE BEING FORMEDWITH PARTS THEREOF ON OPPOSITE SIDES OF SAID INTERCONNECTING PORTION TORETAIN SAID PROTECTOR IN PLACE SO LONG AS SAID TOOTH IS POSITIONED INSAID SOCKET.